Electric-light projecting reflector



March 21, 1950 B. J. PIQUE ELECTRIC-LIGHT PROJECTING REFLECTOR Filed Oct. 17, 1947 INVENTOR Patented Marl 21, 1950 ELECTRIC-LIGHT PROJECTING REFLECTOR Baudllio J esl'is Plqu, Marianne Township, Habana, Cuba Application October 17, 1947, Serial No. 780,477

3 Claims.

My invention relates to an electric-light projecting reflector which comprises an arrangement to project a pencil of bright beams limited horizontally at the top and diverging uniformly downwards; means to dim and diffuse the direct light rays from the light source to an exterior zone comprised between the upper-limit of the divergent pencil and a definite angle over said limit; and means to change the divergent pencil, projecting it merely to the central zone of divergence.

More particularly my invention relates to an electric light projecting device which comprises a compound light source constituted by three single light sources adapted to fulfil two functions in conjunction with two displaced focal points related in combination with a true paraboloidal light concentrating surface having the lower-half part displaced forwards; and a cover glass constituted with a determined part made frozen and colored from its horizontal central line to a deflnite curve line over said central line.

One of the advantages of such light projectors is that they may be made commercially practicable to provide safety headlamps for use on,

automobiles, trucks, airdromes, etc. Another advantage is possible to change the action of the compound light source, reducing the projected field of such divergent pencil of bright beams.

Another advantage of this light projector is the adaptation of a cover glass constituted with a determined part made frozen and colored, apt to diminish the direct light rays, from the light source, that passing through it attain an exterior zone of diffused light comprised between a horizontal plane and a definite angle over the horizontal plane.

Light projectors have heretofore been disclosed in which the reflecting surfaces are different curves to project the beams in desired direction, but these compound surfaces are objectionable because wrought surfaces are not as extremely accurate as a surface made in physical process as the paraboloid, and distortion of the reflected light beams are obtained.

It is known that the best concave surface produced with extreme accuracy is the paraboloid of revolution, because when a liquid body is contained in a receptacle which rotates uniformly, the surface of the liquid takes the form of an accurate paraboloid. The natural surface of liquids in absolute or relative state of repose are extremely accurate. When this liquid is due to a solid body in fused condition by heat, and is contained in a receptacle which rotates uniformly,

and then being cooledslowly while continuing at the same angular velocity. the liquid body takes the solid form of the paraboloid as the pattern. This pattern, with the accurately formed paraboloidal surface, may be cut asunder through a plane holding the axis of the paraboloid, and then both halves may be joined with the displacement required to both focal points. Taking from such pattern the curvature of the surface of the plunger of the pressing apparatus, the reflector section or displaced paraboloidal portions may be made with extreme accuracy by pressing, particularly when made of a glass having a low coefficient of expansion, such as that commercially known as Pyrex" and described and claimed in the United States Patent No. 1,304,623, Sullivan et al., issued May 2'7, 1919.

Until now, the light projectors have been proposed with the filament centered at the focus of the paraboloidal reflecting surface, it is correct, however, when the middle of filament coincides with the focus, it has a half part at each side of said focus, and the light rays coming from the front part of the filament to the lower-half part of the paraboloidal reflecting surface are reflected inclined upward, and the light rays coming from the back of the filament to the upper half part of the paraboloidal reflecting surface are reflected inclined upward. These light rays reflected inclined upward, and the direct light rays inclined upward from the filament, present an obstacle in the way when their are lit with intensity.

One of the objects of my invention is to provide means in an adaptation for light projectors in which the above-mentioned disadvantages will be avoided.

Another object of my invention is to provide a compound light source constituted by three single light sources, as filaments or any other sources, one of them centered and'connected independently; these three single light sources are positioned transversely on the same horizontal plane, and located with its width inter-limited between two focal points displaced jointly with the upper and lower halve parts, respectively, of a true paraboloidal light-concentrating surface; where from this arrangement will project a divergent pencil of bright beams limited horizontally at the top and diverging uniformly downwards; furthermore, when the centered light source is lit alone, the divergent pencil will be projected only to the central zone of divergence.

A further object of my invention is the provision of a cover glass constituted with a determined part made frozen and colored from its horizontal central line to a determined upper curve line, apt to dim the diffuse the direct light rays from the light source to an exterior zone comprised between the horizontal upper limit of the divergent pencil and a determined angle over said limit.

Other objects and advantages of my invention will appear from the following description with reference to the accompanying drawings, in which Figure 1 is a vertical sectional view of a. light projecting device showing'my invention comprised in an adaptation; Figure 2 is a horizontal sectional view taken on the line 2-2 of Fig. 1; Figure 3 is the same horizontal sectional view taken on the line 22 of Fig. 1, showing another adaptation of the displaced halves paraboloids; Figure 4 is a. cross-section view taken on the line 4-4 of Figs. 1, 2 and 3, showing at each side of the dotted line the views according to Figs. 2 and 3, respectively.

Referring to the drawings. particularly Fig. 1, a reflector member 5 having inner preformed paraboloidal surface 8-1, with the lower half part I displaced forwards. The said reflector member 5, with the displaced inner surfaces 6 and I, are preferably made of low-expansion glass, since the plastic glass conforms precisely to the curvature of the accurately formed displaced surfaces of the plunger of the pressing apparatus.

A metallic coating 3-4 applied on the inner surfaces 61, to provide the half paraboloidal light-concentrating surface I with the geometrical focus at inner point F1, and the half paraboloidal light-concentrating surface 2 displaced forward in order to advance its geometrical focus to the front point F2 on the same axis.

The cross-section views taken on the lin 4-4 of Figs. 1, 2 and 3, showed in Fig. 4, shows at each side of the dotted line the front view of the paraboloidal reflecting surfaces I and 2. The form showed at the right side of the dotted line, from observer, is according to Fig. 2, here the extreme points In and II, of the inner surfaces 6 and I. are seperated with each other, forming at the front a discontinued ring. And in the form showed at the left side of the dotted line of Fig. 4, is according to Fig. 3, where the two halves surfaces 6 and I are displaced from their vertices 8 and 9, and coinciding in the extreme points I and I I, forming at the front a circular section.

Up to here, being an adaptation of the complementary parts to combine with the novelty as follows: I

A compound light source constituted by three single light sources I2, I 3 and I4, which may be three filaments, located horizontally in the same plane of displacement of the displaced surfaces I-6 and 2-'I, and positioned on transversal sections inter-limited in conjunction between both focal points F1 and F2. The light source I2 is located with its middle section tangent to the focal point F1 correspondent to the upper-half paraboloidal surface I; and the light source I4 is located with its middle section tangent to the focal point F2 correspondent to the lower-half paraboloidal surface 2; these two light sources I2 and I4 are fixed and connected by means of the conductor members I and IE that are extended to the exterior of the reflector member 5. The light source I3 is located at the middle between the two light sources I2 and I4, and is fixed and connected independently by means of other two conductor members I1 and I8 that are extended to the exterior of the reflector member 5. The middle 4 sections of the three single lightsources I2, II and I4, are in the same lineal direction between the two focal points F1 and F2.

The compound light source I2-I3I4, when if being three filaments should be enclosed in an envelope that is not shown in the drawings, or without envelope if the reflector member 5 were sealed with the cover glass I! together.

Referring to Fig. 1, all light rays coming from the inner focal points F1 to the upper-half paraboloidal reflecting surface I, are reflected horizontally, and all light rays coming from the front focal point F2 to the same upper-half reflecting surface I, are reflected downwards. Fin'thermore, the light rays comin from the front focal point F2 to the lower-half paraboloidal reflecting surface 2, are reflected horizontally, and the light rays coming from the inner focal point F1 to this lower-half reflecting surface 2, are reflected downwards. Hence, when the light sources I2, I3 and I4 are lit'together, the light rays propagated toward both upper and lower halves paraboloidal reflecting surfaces I and 2, will be reflected forming a divergent pencil of bright beams limited horizontally at the top and divergin uniformly downwards. When the centered light source I3 is lit alone, the pencil of bright beams will be propagated solery to the central zone of divergency.

A cover glass I9, constituted with a determined part 20 made frozen and colored, from the horizontal central line 22 to a determined upper curve line 2|, showed in dotted line in Figs. 1 and 4.

The direct light rays propagated from the light source to the exterior, in the direction of a determined zone comprised between a horizontal plane and a deflnite angle over the horizontal plane, will be interfered by the cover glass part 2| made frozen and colored. These light rays that pass through the frozen and colored glass part 20, must be dimmed and diffused, obtaining with it to make in the way a safety high zone of dimmed and diffused light, where it is coming front the opposite driver.

The appropriate color to dim the light with health use is attained mixing the glass part 24 with a proportion of colors of two parts of yellow, one part of blue and one part of red, obtaining a dimmed and diffused light of grayish green color.

The cover glass I8 and the frozen and colored part 20 may be made of low-expansion glass, and thus, them may be welded through the line of joints 2| and 22.

The reflector member 5, with the displaced-preformed interior paraboloidal surfaces 8 and I, may be made of glass or any other proper material. The paraboloidal halves surfaces 6 and 1 may be made together with the reflector member 5 by a pressing apparatus with accurately formed displaced surfaces. The reflector member 5 with the displaced halves paraboloid 6 and I, may be made of low-expansion glass.

When the reflector member 5 is made metallic, the displaced interior surfaces 6 and I may be the correspondent paraboloidal reflecting surfaces, without the coatings 3 and 4.

The two halves paraboloidal surfaces 6 and 'I, with their respectively reflecting surfaces I and 2, may have equal focal distances when said surfaces I-6 and 2I are displaced with each other with the same displacement required to the focal points F1 and F: with each other, with respect to the width of the light source.

When both displaced halves paraboloidal surfaces l-l and 2--I have different focal distances. the displacement required to said surfaces l---! and 2-1 will be according to the relative sep tion to the focal points F1 and P2, with respect to the width of the light source.

As a suitable adaptation, when is desired a greater width of the light source I2-lI-ll, together with the separation of both focal points F1 and F2, and lesser displacement of both paraboloidal halves surfaces l-- and 2-1, the upperhalf surface must have lesser focal distance than the lower-half surface 2-1; and it is possible to make coinciding the extreme points II and II, at the periphery of the displaced halves surfaces i-J and 2|, having at the front continued ring section. Referring to Fig. 3, and considering a parabolical section ll9'll' of a surface I, shown in dotted line, with the vertex coinciding at vertex point 8 of the parabolical section lH-ll of the inner surface 6. Taking the coincided points 8 and 8' as origen of rectangular coordinates with the X-axis coinciding with the paraboloidal axes. The equations of the two parabolic sections are:

Y =4P1X (1), and Y =4P:X (2) Where the expression P1 is the geometric focal distance correspondent to the interior concave section Ill-t-IO, and the expression P2 represent the geometric focal distance correspondent to the concave section li'-Q'-il'. Here, the focal distance P1 must be shorter than the focal distance P2.

Considering that the extreme point II have the same ordinate b as the extreme point II, and solving both Equations 1 and 2 with the ordinate Y=b we'll have that b*=4P1X1=4P:Xa (3). From Equation 3 we have that: P:/P1=X1/Xz (4), subtracting the unit at both members the expression (Xi-X2) is the distance from the extreme points ii and it, one from another.

If the parabolic section li'-l'll' is displaced a space (Xi-X2) from its position to the position H9ll, the two parabolic sections "-8-" and ll8--il will coincide at the extreme points I. and i l correspondent to the horizontal joint lil89--il of the upper-half and lower-half of the reflector member 5. After the displacement of the interior surface 1, together with the reflecting surface 2, the space W comprised between the two focal points F1 and F: must be equal to the width of the light source, here the three filaments I 2--|IH. The algebraic expression of W will be:

Making the displacement (Xi-X2) =%W ('7); from Equations 6 and 7 we will have that (P2P1)= W (8). Substituting these two values 7 and 8 in the Equation 5, we have that 2P1=Xz (9). Eliminating X: from Equations 7 and 9, and solving for X1 value, we have that X1=2(P1+%W) (10). Substituting this value of X1 from Equation 10 at the Equation 3:

P1+ WP1%b=0 (11) Solving by P1 in this Equation 11, we will have that:

P1=:i:% W+9/2b%WI 12 Eliminating P1 from Equations 8 and 9, and solving by K2 value, we have that O at the Equation 3: P:'- %WPa-%b'=-0 (l4) {and solving by P: from Equation 14:

P,=- a WW 2v+mv (15) Looking at the Equations 12 and 15, with the real positive values, the general equation of PI and P2 willbe:

P= wwu-o/zvi ew (it) P is for P1 and P: values, being b the half diameter of the reflector member I, and W is the space comprised between the two focal points F1 and h, equal to the width of the light source.

From Equation 9 we see that the focal point I": is located at the middle of the reflector member I.

Let us observe in Fig. 1, that the reflected light rays inclined downwards, v form a determined angle a with the horizontally-reflected light rays, increasing said angle a from the vertices I and 9 to the upper and lower vertical part of the middle point between the focal points F1 and F2, on the reflecting surfaces I and 2, respectively, where the angle a is maximum. The maximum angle a on the lower-half reflecting surface 2 is greater than the maximum angle a on the upper-half reflecting surface I. These maximum values of a are measure of the geometric relation is the gradient relation of the maximum inclination of the light rays, and Ya is the ordinate correspondent to the middle point between the focal points F1 and F2, where Xul=Pl+ /2W (18), and Xa:=P: W (19).

Solving for N in Equation 17:

N =Ya/ W-W/4Ya (20) As an example: a reflector of 6 inch of diameter with a light source of A inch of width: b=3" and W= By the Equation 16, Pi=0.981 inch, and P:=l. 47 inch. By the Equations 1,

- 18 and 20, Ni=4.34 to l; and by the Equations 2, l9 and 20, N2=3.934 to 1. If the reflector is located at 3 feet over the floor, the maximum-inclined reflected rays will attain the floor at 3x4.34=13 feet, and 3x3.934=11.8 feet, from the reflector.

As a greater width of the compound light source l2ll-l4 jointly with the separation of both focal points F1 and F2, the pencil of bright beams will diverge downward more amply, obtainir foresaw desired amplitude. Hence, it is not new to use lens here instead of cover glass.

What I claim as new and desire to secure by Letters Patent is:

1. In a light projecting device comprising true paraboloidal light-concentrating surface preformed with the lower half part displaced forward at the same axis in order to have advanced its focal point in relation to the focal point of the upper half part, a light source positioned transversely horizontal with its width inter-limited between both displaced focal points, and a cover glass constituted with a determined part made frozen and colored from its horizontal central line to a definite curve line over the central line, substantially as described to avoid the propagation of direct and indirect light rays inclined upward.

2. In a light projecting device comprising true paraboloidal light-concentrating surface preformed with the lower half part displaced forsubstituting this value of X: from Equation 13, ward at the same axis in order to have advanced 7, its focal point in relation to the focal point of the upper half part, a compound light source constituted by three single light sources positioned transversely on a same horizontal plane with their width in conjunction inter-limited between both displaced focal points, one of said single light source being centered and connected independently from both other substantially as described to fulfill two independent functions, one projecting a divergent pencil of bright beams diverging uniformly downwards and limited horizontally at the top, and other one projecting the pencil mere- 1y to the central zone of dlvergency.

3. In a light projecting device comprising true paraboloidal light-concentrating surface preformed with the lower half part displaced forward at the same axis in order to have advanced its focal point in relation to the focal point of the upper half part, a compound light source constituted by three single light sources positioned transverselly on a same horizontal plane with their width in conjunction inter-limited between BAUDILIO JEst'Is PIQUE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,284,019 Wood Nov. 5, 1918 1,625,946 Laird Apr. 26, 1927 1,670,837 Blackmore May 22, 1928 1,998,187 Conti Apr. 16, 1935 2,148,315 Wright Feb. 21, 1939 2,191,546 Schreiber Feb. 27, 1940 

